低温环境下桥梁用结构钢疲劳寿命估算方法

在现有研究成果的基础上,基于断裂力学理论提出了适用于桥梁结构钢的低温疲劳寿命估算方法。利用室温环境下的疲劳性能参数和低温环境的基本力学性能参数对低温环境下的疲劳极限、疲劳裂纹扩展门槛值等进行预测,建立疲劳裂纹扩展速率模型,应用等效初始裂纹法估算低温环境下桥梁钢的疲劳寿命,并通过塑性区裂纹尺寸修正进行低周疲劳寿命预测。通过算例表明,该方法能够较为准确的预测Q345qD钢试件的拉伸疲劳寿命,从而避免了成本高昂的低温疲劳试验,为钢结构桥梁的低温疲劳分析提供简便而实用的依据。

Estimation of fatigue life of structural steel for bridge at low temperature

A low temperature fatigue life estimation method for bridge structural steels is proposed based on fracture mechanics theory.The fatigue limit and fatigue crack growth threshold is predicted by using fatigue performance parameters in room temperature and basic mechanical properties parameters in low temperature environment.The fatigue crack growth rate model is established.The fatigue life of bridge steel in low temperature environment is estimated by equivalent initial crack method,and the plastic zone is adopted.The low cycle fatigue life is predicted by crack size modification.The example shows that this method can accurately predict the tensile fatigue life of Q345qD steel specimens,thus avoiding costly low-temperature fatigue tests,and providing a simple and practical basis for the low-temperature fatigue analysis of steel structure bridges.